Use of probabilistic and statistical methods for determination of the sources of water flow in candidate wells for water shut-off works (on example of the Visean reservoir of the Perm region field)

• Main Author: Darya A. Kudryashova
• Format: Article
• Language: English
• Published: Perm National Research Polytechnic University 2018-03-01
• Series: Perm Journal of Petroleum and Mining Engineering
• Subjects: Visean reservoir; well; watercut; water shut-off works; source of water inflow; water breakthrough along the productive formation; pumped water; aquifer water; Student’s t-criterion; distance from the lower perforation object to the water-oil contact; thickness of water inflow interval; current density of water produced; discriminant analysis; Wilks' Lambda; classification function; posteriori probability
• Online Access: http://vestnik.pstu.ru/get/_res/fs/file2.pdf/7422/Use+of+probabilistic+and+statistical+methods+for+determination+of+the+sources+of+water+flow+in+candidate+wells+for+water+shut-off+works+%28on+example+of+the+Visean+reservoir+of+the+Perm+region+field%29file2.pdf

Today, the problem of production of surplus associated water is particularly actual because of transition of fields to the final stages of development. Water shut-off works are the main method to combat the increased water cut of wells of modern fields. One of the most important stages in water shut-off works is the selection of candidate wells and determination of their sources of water inflow which depend on the geological structure of an oil reservoir and well technical state. Technical reasons of water inflow to wells include leakage of a production string and annular circulation. Geological reasons include lift of water-oil contact to the bottom hole, breakthrough of water along the productive formation, fractures between wells or formations. The article discusses production wells of the Visean reservoir of the Perm region field with shut-off works done. Wells are divided according to the most common sources of water inflow into two groups such as a breakthrough in the productive formation of pumped or aquifer water. To analyze the average values of geological and technological parameters of the two groups of wells obtained from the field data the Student's t-criterion is used. Among the analyzed parameters the distance from the lower perforation to the water-oil contact, formation thickness and thickness of the interval of water inflow are statistically significant. To determine the sources of water inflow for 19 candidate wells of the Visean reservoir of the Perm region field a discriminant analysis is performed. Based on the table of values of a posteriori probabilities, it is revealed that 4 wells of 19 candidate wells for water shut-off works are flooded due to breakthroughs of pumped water through the productive formation, 4 wells are flooded by aquifer water. The 11 remaining candidate wells are likely to have another source of water.